Metal refining agent consisting of al-mn-ca alloy



NOV. 17, 1970 TOHEl OToTANl ETAL 3,540,882

METAL REFINING AGENT CONSISTING OF AQ-MN'C ALLOY Filed July 19, 1968 2 Sheets-Sheet 1 Nov. 17, 1970 TOHEILOTQTANI ETAL 3,540,882

METAL REFINING AGENT CONSISTING OF Al-MN-Ca ALLOY Filed July 19, 1968 2 Sheets-Sheet 2 base Time (in @S x 2mm QE U ited States Patent 3,540,882 METAL REFINING AGENT CONSISTING 0F Al-Mn-Ca ALLOY Tohei Ototani, Yasuji Kataura, and Shingo Koike, Sendai, Japan, assignors to The Research Institute for Iron, Steel and Other Metals of the Tohoku University, Sendai, Japan Filed July 19, 1968, Ser. No. 746,175 Claims priority, application Japan, July 24, 1967, 42/ 47,186 Int. Cl. C22c 31/00, 21/00 U.S. Cl. 75-134 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a metal refining agent comprising Al-Mn-Ca alloy essentially consisting of 15 to 75% of aluminum, 5 to 25% of calcium and 5 to 80% of manganese, and more particularly to a metal refining agent comprising Al-Mn-Ca alloy consisting of to 75% of aluminum, 5 to of calcium, 5 to 80% of manganese, and up to 5% of a deoxidizing element selected from the group consisting of rare earth metals, silicon, zirconium, titanium, niobium, boron, vanadium, and alkaline earth metals excluding calcium.

An object of the present invention is to provide a metal refining agent essentially consisting of an Al- Mn-Ca ternary alloy. In the refining agent of the inventio, aluminum having a high afiinity with both manganese and calcium is used in conjunction with manganese and calcium, as manganese and calcium alone do not constitute any alloy or compound.

For a better understanding of the invention, reference is made to FIG. 1 of the accompanying drawing in which the single drawing is a ternary characteristic diagram of Al-Mn-Ca alloy, according to the present invention, shown with binary characteristic diagrams on each side of the triangular ternary characteristic diagram.

FIG. 2 is a characteristic diagram showing each datum in the comparative experiments of III and IV obtained by adding aluminum only an Al-Ca-Mn alloy, respectively, With steels to be refined.

Referring to the diagram of FIG. 1, particularly in the Mn-Ca binary characteristic diagram thereof, it is generally believed that manganese and calcium do not produce either a solid solution or a compound consisting of the two elements alone. On the other hand, if there could be produced an alloy consisting of manganese and calcium, such alloy Would widely be used in refining irons, steels, and nonferrous alloys. There are known such calcium alloys as calcium-silicon alloys, calciummagnesium alloys, calcium-aluminum alloys, calciumlithium alloys, calcium-manganese-silicon alloys, and calcium-magnesium-silicon alloys. The aforesaid alloys, except the calcium-manganese-silicon alloys, have a comparatively small specific gravity. Therefore, if such alloys are thrown into a molten metal bath, the refining agent will float on the surface of the metal bath and their dispersibility in the metal bath would be small. Therefore, the reaction velocity of calcium added with a refining ice agent well known in the prior art is rather low, and the amount of calcium available for refining is not so large, since a sizable amount of calcium is transferred into slugs as a loss. In other Words, such alloys have a disadvantage in that when a large amount of the alloy is added with the metal bath only wasteful consumption of the calcium is increased Without causing any improvement in the homogeneity and velocity of the refining reaction.

Although the ternary calcium-manganese-silicon alloys have a specific gravity comparatively larger than that of other calcium alloys, the silicon contained in the ternary alloys forms inclusion particles consisting of silicic acid or silicates when such alloys are used for refining molten metal in a bath, which silicic acid particles or silicate particles do not lift to the surface of the bath, but become suspended and remain as nonmetallic inclusion particles. It is known that such silicic acid and silicates act to considerably deteriorate the machinability of the metal thus refined.

The inventors had considered the fact that known refining agents consisting of calcium alloys have a low yield of calcium due to the small specific gravity thereof, and that such agents tend to deteriorate the machinability of the refined metal due to the formation of nonmetallic inclusion remaining in the refined metal and consisting of silicic acid or silicates. Further they have conducted a series of studies on metal refining agents consisting of a new calcium alloy having a specific gravity larger than that of known calcium alloys and containing not more than 5% of silicon, so as to eliminate the possible cause of deterioration of machinability. As a result of these studies, the inventors have developed metal refining agents Which can be used as a universal agent for refining not only iron and steel but also various alloys consisting of nonferrous alloys, especially nickel alloys and copper alloys. As a result of their studies, the inventors have found that aluminum having a high aflinity for both manganese and calcium can be used to form Al-Mn-Ca alloys, although manganese and calcium do not produce any alloys by themselves. In other words, the inventors have found that alloys consisting of 15 to of aluminum, 5 to 25 of calcium, and 5 to of manganese can be used to obviate the aforesaid difficulty of known refining agents.

The inventors have disclosed, in their preceding U.S. Pat. No. 2,950,187, a refining agent of iron and steel consisting of an iron-calcium base alloy, characterized by consisting of 80 to 10% of iron and 20 to 5% of calcium, as basic components, and in addition, 55 to 5% of aluminum and 55 to 5% of manganese which have a high affinity with both iron and calcium.

The preceding U.S. patent of the present inventors disclosed calcium alloys usable for refining iron and steel, which alloys contain more than 10% of iron, and hence, the difference between the agent including more than 10% of iron according to the aforesaid preceding U.S. patent and the metal refining agent excluding iron according to the present invention is in the content of iron and the object of using the refining agents. The present invention intends to use the agent not only for refining iron and steel, but also for refining nonferrous alloys, especially nickel alloys and copper alloys. The object of the present invention is to provide a metal refining agent especially nickel alloys and copper alloys. The object of contining no iron. If refining agents consisting of calcium alloys containing iron are used for refining nickel alloys and copper alloys, the moldability and machinability of the nickel alloys and copper alloys are deteriorated, and hence, calcium alloys containing iron cannot be used for refining such nonferrous alloys.

The inventors have studied and searched for alloy com positions usable for metal refining agents which do not contain iron, and consequently, discovered a universal metal refining agent applicable to refining of nickel alloys and copper alloys.

When nickel-aluminum alloys are refined by using the refining agent according to the present invention, a suspension of A1 in the molten bath of such alloys is reduced, to improve its moldability. When the refining agent of the present invention is used for refining copper alloys, the copper alloy products obtained thereby have a very low oxygen content and improved machinability and moldability. If the refining agent of the present invention is applied to the refining of steel, excellent cleanliness and outstanding results in the step cutting test are achieved, and in addition, its machinability is also improved.

In the ternary characteristic diagram of Al-Mn-Ca alloys of FIG. 1, with binary characteristic diagrams attached thereto on each side of the triangular ternary characteristic diagram, the Mn-Ca region thereof illustrates a monotectic reaction, and such reaction terminates at more than 32.5% of aluminum content. In the figure, a pentagon ABCDE represents the composition range of the metal refining agent of the present invention.

If the refining agent of the present invention is added with up to of another deoxiding element selected from the group consisting of rare earth metals, silicon, zirconium, boron, vanadium, titanium, niobium and alkaline earth metals, excluding calcium, such as magnesium, barium, strontium, and lithium, then the refining effects of the agent can be further improved.

The reasons for limiting the alloy composition of the refining agent of the present invention to the aforesaid range will now be described.

(1) Aluminum: 15 to 75 %.As shown in the ternary characteristic diagram of the Al-Mn-Ca alloy of FIG. 1, if the content of aluminum is less than 15%, it is difficult to form a ternary alloy. On the other hand, if the aluminum content exceeds 75%, the contents of calcium and manganese are accordingly reduced from the effective amount, and hence, it becomes diflicult to make its specific gravity larger than that of conventional refining agents known in the prior art, and also the advantages of the ternary alloys, constituting the characteristics of the present invention, are lost.

(2) Calcium: 5 to 25 %.The characteristic eifects of calcium in the refining agent of the invention cannot be achieved for a calcium content less than 5%, while for a calcium content in excess of 25%, the yield of calcium is reduced, in spite of the increase of the cost of the alloy, and hence the upper limit of the calcium content is set at 5%.

(3) Manganese: 5 to 80%.If the manganese content is less than 5%, the object of adding manganese cannot be achieved, while if the manganese content exceeds 80%, no effective ternary alloy can be formed, as shown in the ternary characteristic diagram.

EXAMPLE 1 In melting an Al-Ni alloy consisting of 4.5% of aluminum and 94% of nickel, the alloy composition was adjusted in a certain predetermined condition by using 200 kg. of electrolytic nickel and the Al-Nn alloy, and then the molten alloy was divided into two parts.

One part of the molten alloy was directly cast and made into rolled soft plates, while the other part of the alloy had added thereto 0.3% of an Al-Mn-Ca alloy consisting of 35.5% of aluminum, 45% of manganese, 19.1% of calcium, and 0.4% of other inevitably introduced ingredients, such as rare earth metals, silicon, zirconium, titanium, niobium, boron, vanadium, and alkaline earth metals excluding calcium, and then formed into rolled soft plates.

The mechanical properties of the thus prepared rolled plates were compared, and the results are shown in the following table.

Elongation was measured just prior to breakdown in the tensile strength test.

EXAMPLE 2 In casting a screw propeller with aluminum bronze consisting of 10.5% of aluminum, 1.5% of manganese, 1.2% of nickel, and the remainder of copper, a molten bath was prepared by melting together 1.3% of copper, 1.3% of manganese, 1.2% of nickel and 10% of aluminum, and then the thus prepared molten metal bath was divided into two parts. One part of the thus divided two parts had added thereto 0.3% of the refining agent according to the present invention consisting of 35.5 of aluminum, 45.2% of manganese, 19.1% of calcium, and the remaining 0.2% of aforesaid ingredients, while the other part of the molten metal bath did not have added thereto the refining agent. The mechanical properties of the samples having added thereto the refining agent ac- The alloy having the refining agent of the present invention added thereto was completely free from pin holes and a fine grain crystal structure was formed. The tests were made on molded test pieces of 26 mm. dia. for the sake of comparison.

EXAMPLE 3 Five kilograms of carbon steel containing 0.42% of carbon was melted by a high-frequency furnace, and the molten bath had added thereto 0.3% of iron-manganese alloy and 0.2% of silicon. Then, the molten bath was divided into two parts, and 0.1% of aluminum was added to one part, while adding 0.22% of ternary alloy refining agent according to the present invention consisting of 45.2% of aluminum, 35.5% of manganese, and 19.3% of calcium into the other part. Both parts of the molten bath were poured into metal molds about ten seconds after the addition of aluminum and the present ternary refining agent, respectively. The oxygen content in the carbon steel before the addition of aluminum and the present Al-Mn- Ca alloy was 0.035%, and such oxygen content was reduced to 0.028% in the part added with aluminum, and to 0.015% in the part added with the present Al-Mn-Ca alloy, respectively (referring to curves A and B in FIG.2).

The ingots thus prepared were forged and rolled, and test pieces were taken for making the test according to the system of Japanese Industrial Standard 3. It was proved that the cleanliness of the sample added with aluminum alone was 0.10%, while that of the sample added with the refining agent according to the present invention was 0.05%. In other words, the percentage of the cleanliness was reduced to one half, by adding the refining agent of the present invention.

EXAMPLE 4 A material having the following steel composition was prepared from electrolytic iron only and was melted by heating in a magnesia lined high frequency induction furnace having a 3.5 kg. capacity.

Steel composition (percent): C, 0.006; Mn, 0.26; Si, 0.19; P, 0.004; S, 0.008.

After the deoxidized preliminary with 0.5% of manganese and 0.2% of silicon at 1600 C. in the argon atmosphere, each molten alloy was sampled in a Tammann crucible with different amounts of aluminum and Mn-Al-Ca alloy having the following composition, and the samples were quenched after 30 seconds and 60 seconds by water.

Alloy composition (percent): Mn, 33.0; A1, 44.9; Ca, 19.2; P, 0.050; S, 0.010; C, 0.06; Si, 4.5; rest other ingredients.

The oxygen content of the cast specimen was determined by the argon carrier fusion method as shown in FIG. 2.

In FIG. 2, curve A illustrates the result of Example 3 in case of adding the base with 0.1% of aluminum, and curve B illustrates the result of Example 3 in case of adding the base with 0.22% of Al-Ca-Mn alloy.

Curve C illustrates the result of Example 4 in case of adding the base with 0.1% of aluminum, and curve D illustrates the result of Example 4 in case of adding the base with 0.1% of said Al-Ca-Mn alloy.

It is obvious that the oxygen content of the steel refined by adding with the present Al-Ca-Mn alloy was remarkably reduced in Example 3 and Example 4.

What is claimed is:

1. A metal refining agent comprising, an aluminummanganese-calcium alloy essentially consisting of 5 to of calcium, 5 to 80% of manganese, and 15 to of aluminum.

2. A metal refining agent comprising an aluminummanganese-calcium alloy consisting of 5 to 25 of calcium 5 to of manganese, 15 to 75% of aluminum, and up to 5% of a deoxidizing element selected from the group consisting of rare earth metals, silicon, zirconium, titanium, niobium, boron, vanadium, and alkaline earth metals excluding calcium.

References Cited UNITED STATES PATENTS 3,000,731 9/1961 Ototani 75-129 3,119,688 l/1964 Rodgers et a1. 75129 3,131,058 4/1964 Ototani 75129 3,304,174 2/ 1967 Ototani et a1. 75122 L. DEWAYNE RUTLEDGE, Primary Examiner E. L. WEISE, Assistant Examiner US. Cl. X.R. 75-l22, 129, 138 

